That podcast actually had a lot of problems. One of them in particular--the study Caroline Pukall discussed when she was interviewed for the podcast, her 2016 work Examining Penile Sensitivity in Neonatally Circumcised and Intact Men Using Quantitative Sensory Testing. (Bossio, JA. Pukall, CF. Steele, SS. Journal of Urology, Vol. 195, No. 6: Pp. 1848-53. June 2016)

That so-called study was rife with methodological and conceptual errors. The bioethicist Brian Earp wrote an in depth critical review of it, Infant circumcision and adult penile sensitivity: implications for sexual experience. (Trends in Urology & Men's Health, Vol. 7, Issue 4: Pp. 17-21. July/August 2016)

The feminist blogger Rebecca Watson also provided a critical commentary of the study on her youtube channel.

Back to the history of the practice--you would likely find a lot of information you're looking for in The riddle of the sands: Circumcision, history and myth. (The New Zealand Medical Journal, Vol. 118, No. 1218. ISSN 1175 8716. July 2005) and The masturbation taboo and the rise of routine male circumcision: A review of the historiography (Journal of Social History, Volume 27: Pp. 737-757. Spring 2003), both by R. J. L. Darby, who is perhaps the foremost living expert regarding the history of circumcision.